Partial Approval and Partial Disapproval of Air Quality Implementation Plans; Arizona; Nonattainment Plan for the Hayden SO2 Nonattainment Area

The Environmental Protection Agency (EPA) is finalizing a partial approval and partial disapproval of an Arizona state implementation plan (SIP) revision for attaining the 2010 1-hour primary sulfur dioxide (SO<INF>2</INF>) national ambient air quality standard (NAAQS or "standard") for the Hayden SO<INF>2</INF> nonattainment area (NAA). This SIP revision (hereinafter called the "Hayden SO<INF>2</INF> Plan" or "Plan") includes Arizona's attainment demonstration and other elements required under the Clean Air Act (CAA or "Act"). The EPA is approving the base year and projected emissions inventories and affirming that the new source review requirements for the area have been met. We are disapproving the attainment demonstration, as well as other elements of the Plan tied to this demonstration, namely, the requirement for meeting reasonable further progress (RFP) toward attainment of the NAAQS, reasonably available control measures and reasonably available control technology (RACM/RACT), enforceable emissions limitations and control measures, and contingency measures.